Do-It-Yourself
EF Y
S.C.
DC Motor Bidirectional Control
With TV Remote
T
his project describes how a DC
motor can be moved in forward
or reverse direction using a TV
or DVD remote control. The goal is
to construct a simple bi-directional
motor driver that uses modulated
vedi
Dwi
Pamarthi Kanakaraja
infrared (IR) 38kHz pulse train for the
purpose without using any microcontroller or programming.
The author’s prototype is shown
in Fig. 1.
Circuit and working
Circuit diagram of the project is shown
in Fig. 2. It is built around IR receiver
module TSOP1738 (IRRX1), decade
counter 4017B (IC2), motor driver
L293D (IC3), PNP transistor BC557
(T1), two BC547 NPN transistors (T2
and T3), 5V regulated power supply
(IC1), and a 9V battery.
The 9V battery is connected
through diode D1 to voltage regulator
7805 to generate 5V DC required for
Truth Table
of L293D Motor Driver
Cases
O0 - high
O1 - high
O2 - high
O3 - high
Q4 - high (Reset)
Fig. 1: Author’s prototype
IRRX1
TSOP
O0
1738
16
VDD
15
RESET
O/P
VCC
GND
1 2 3
R1
47E
C1
4.7u
16V
1
D1
1N4007
BATT.1
9V
T1
BC557
14
IC1
7805
R2
150K
3
2
C3
1u
16V
R3
1K
C2
100u
16V
13
CLK
IC2
4017B
CLK EN
2
O2
4
O3
7
O4
10
O5
1
O6
12
8
CO
Vss
6
O8
9
O9
11
LED1
CLOCK
PULSE
R5
1K
T2
15
BC547
10
7
R6
1K
5
O7
IN2
1
1
1
0
1
Motor status
Off state
Forward direction
Off state
Reverse direction
Off state
R4
1K
3
O1
IN1
1
0
1
1
1
Table 1
2
9
1
EN2
EN1
8
16
VCC
IN4
IC3
L293D
IN3
IN2
IN1
VREF
11
OUT3
14
OUT4
OUT2
GND
GND
GND GND
13
12
5
OUT1
6
M1
3
4
M1 = 5V DC MOTOR
R7
1K
T3
BC547
GND
Fig. 2: Circuit diagram of the DC motor driver
64
June 2021 • electronics For You
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Do-It-Yourself
Fig. 3: Actual-size PCB layout
Parts List
Semiconductors:
IC1
- 7805, 5V voltage regulator
IC2
- 4017B decade counter
IC3
- L293D motor driver
D1
- 1N4007 rectifier diode
LED1
- 5mm LED
T1
- BC557 PNP transistor
T2, T3
- BC547 NPN transistor
IRRX1
- TSOP1738 IR receiver
Resistors (all 1/4-watt, ±5% carbon):
R1
- 47-ohm
R2
- 150-kilo-ohm
R3-R7
- 1-kilo-ohm
Capacitors:
C1
- 4.7µF, 16V electrolytic
C2
- 100µF, 16V electrolytic
C3
- 1µF, 16V electrolytic
Miscellaneous:
BATT.1
- 9V battery
M1
- 5V/12V DC motor
- Jumper wire
- 16-pin IC socket
- Heat-sink for IC1
the project. Capacitor C2 (100µF, 16V)
is used for ripple rejection.
Under normal condition, output
pin 3 of IR module IRRX1 is at logic
high, which means transistor T1 connected to it is cut-off and so its collector
terminal is at logic low. The collector
of T1 drives the clock pulse of decade
counter IC2.
On pointing the remote towards
IR module and pressing any key, the
module receives the 38kHz IR pulses
from the remote control. These pulses
are inverted at the collector of T1 and
given to clock input pin 14 of decade
counter IC2.
The arriving IR pulses increment the
decade counter at the same rate (38kHz)
but because of the presence of RC filter
(R2=150k and C3=1µF) at clock input
pin 14 of IC2, the train of pulses appears
as a single pulse at the counter. Thus, on
pressing each key, the counter advances
by a single count only.
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Fig. 4: Components layout of the PCB
When the remote’s key is released,
capacitor C3 discharges through resistor R2 and the clock line becomes
zero. So every time the user presses
and releases a key on the remote, the
counter receives a single pulse at its
clock input and LED1 glows to confirm
that the pulse has been received.
During operation there can be five
possibilities:
Case 1. When the remote’s key
is pressed, the first pulse arrives and
the O0 output of decade counter (IC2)
goes high while pins O1 through O9
are low, which means transistors T2
and T3 are in cut-off state. The collectors of both the transistors are pulled
to high state by 1-kilo-ohm resistors
(R4 and R6), so both the input terminals IN1 and IN2 of motor driver
L293D (IC3) become high. At this
stage, the motor is in off state.
Case 2. When a key is pressed
again, the second pulse arriving at
CLK line increments the counter by
one. That is, when the second pulse
arrives, O1 output of IC2 goes high,
while the remaining outputs are low.
So, transistor T2 conducts and T3 is
cut-off. Which means the voltage at
collector of T2 goes low (IN1 of IC3)
and voltage at collector of T3 becomes
high (IN2 of IC3) and the inputs IN1
and IN2 of motor driver IC3 become 0
and 1, respectively. In this condition,
the motor rotates in forward direction.
Case 3. When a key is pressed
once again, the third pulse arriving at
CLK line increments the counter by
one again. So O2 output of IC2 goes
high. As nothing is connected to O2
pin and output pins O1 and O3 are
low, so both transistors T2 and T3 go
to cut-off state. Collector terminals of
both the transistors are pulled to high
state by 1-kilo-ohm resistors R4 and
R6, which means input terminals IN1
and IN2 of IC3 become high. At this
stage, the motor is again in off state.
Case 4. When a key is pressed once
more, the fourth pulse arriving at CLK
line increments the counter by one for
the fourth time. Now O3 output of IC2
goes high, while the remaining outputs
are low, so transistor T3 conducts.
Which means the voltage at collector of
T2 becomes high (IN1 of IC3) and voltage at the collector of T3 becomes low
(IN2 of IC3). So, inputs IN1 and IN2 of
IC3 are at 1 and 0 levels, respectively.
In this condition, the motor rotates in
reverse direction.
Case 5. When a key is pressed for
fifth time, the fifth pulse arriving at
CLK line increments the counter by one
once again. Since O4 (pin 10 of IC2) is
wired to Reset input pin 15 of the IC2,
pressing for the fifth time brings the
decade counter IC back to power-onreset condition with O0 high.
Thus, the circuit operates as a
bi-directional motor driver that is
controlled with an infrared remote
control.
Construction and testing
The circuit can be assembled on a
Veroboard or a PCB whose actual-size
layout is shown in Fig. 3. The components layout for the PCB is shown
in Fig. 4.
After assembling the circuit, connect 9V battery across BATT.1. Refer
the Truth Table (Table 1) for operation and follow the steps described in
Case 1 through Case 5 above.
Pamarthi Kanakaraja is an
assistant professor (R&D cell) at
K.L. University, Vaddeswaram,
Guntur district, Andhra Pradesh
electronics For You • June 2021
65